api: nvim_list_uis #8004

ref #7438
closes #4842

src/nvim/api/vim.c

@@ -35,6 +35,7 @@
 #include "nvim/os/input.h"
 #include "nvim/viml/parser/expressions.h"
 #include "nvim/viml/parser/parser.h"
+#include "nvim/ui.h"
 
 #define LINE_BUFFER_SIZE 4096
 
@@ -1468,3 +1469,12 @@ Float nvim__id_float(Float flt)
 {
   return flt;
 }
+
+/// Gets a list of dictionaries representing attached UIs.
+///
+/// @return Array of UI dictionaries
+Array nvim_list_uis(void)
+  FUNC_API_SINCE(4)
+{
+  return ui_array();
+}

src/nvim/ui.c

@@ -526,3 +526,19 @@ bool ui_is_external(UIExtension widget)
 {
   return ui_ext[widget];
 }
+
+Array ui_array(void)
+{
+  Array all_uis = ARRAY_DICT_INIT;
+  for (size_t i = 0; i < ui_count; i++) {
+    Dictionary dic = ARRAY_DICT_INIT;
+    PUT(dic, "width", INTEGER_OBJ(uis[i]->width));
+    PUT(dic, "height", INTEGER_OBJ(uis[i]->height));
+    PUT(dic, "rgb", BOOLEAN_OBJ(uis[i]->rgb));
+    for (UIExtension j = 0; j < kUIExtCount; j++) {
+      PUT(dic, ui_ext_names[j], BOOLEAN_OBJ(uis[i]->ui_ext[j]));
+    }
+    ADD(all_uis, DICTIONARY_OBJ(dic));
+  }
+  return all_uis;
+}

test/functional/api/vim_spec.lua

@@ -745,7 +745,7 @@ describe('api', function()
     end)
   end)
 
-  describe('list_runtime_paths', function()
+  describe('nvim_list_runtime_paths', function()
     it('returns nothing with empty &runtimepath', function()
       meths.set_option('runtimepath', '')
       eq({}, meths.list_runtime_paths())
@@ -998,4 +998,43 @@ describe('api', function()
         it, _check_parsing, hl, fmtn)
   end)
 
+  describe('nvim_list_uis', function()
+    it('returns empty if --headless', function()
+      -- --embed implies --headless.
+      eq({}, nvim("list_uis"))
+    end)
+    it('returns attached UIs', function()
+      local screen = Screen.new(20, 4)
+      screen:attach()
+      local expected = {
+        {
+          ext_cmdline = false,
+          ext_popupmenu = false,
+          ext_tabline = false,
+          ext_wildmenu = false,
+          height = 4,
+          rgb = true,
+          width = 20,
+        }
+      }
+      eq(expected, nvim("list_uis"))
+
+      screen:detach()
+      screen = Screen.new(44, 99)
+      screen:attach({ rgb = false })
+      expected = {
+        {
+          ext_cmdline = false,
+          ext_popupmenu = false,
+          ext_tabline = false,
+          ext_wildmenu = false,
+          height = 99,
+          rgb = false,
+          width = 44,
+        }
+      }
+      eq(expected, nvim("list_uis"))
+    end)
+  end)
+
 end)